What is a WAN port?
A wide area network (WAN) port on a router connects it to the Internet via a modem while the local area network (LAN) ports connect all the computers and other client devices to each other.
If you look at these ports on a router, you'll see the LAN ports grouped together and the WAN port set apart and often bearing a different color. The WAN port is the gateway through which all devices connected to LAN ports can access the internet.
Some businesses use routers with two WAN ports so that they can use separate Internet services on each.